Keutschacher See is a lake of Carinthia, Austria. It is sixth-largest in Carinthia, with an area of 1.32 km2 (0.51 sq mi). It has a Neolithic stilt settlement, discovered by Ferdinand von Hochstetter in 1864.

Carinthia is the southernmost and least densely populated Austrian state, in the Eastern Alps, and is noted for its mountains and lakes. The main language is German. Its regional dialects belong to the Southern Bavarian group. Carinthian Slovene dialects, forms of a South Slavic language that predominated in the southeastern part of the region up to the first half of the 20th century, are now spoken by a small minority in the area.